New Design Configuration of Steel Catenary Risers With Pull-Tube for Spars

2011 ◽  
Author(s):  
Shan Shi ◽  
Charlie Mao ◽  
Jenny Yang ◽  
Nishu Kurup
Keyword(s):  
Finite Element ◽  
Finite Element Program ◽  
Additional Advantage ◽  
Nonlinear Contact ◽  
Element Program ◽  
Steel Catenary Risers ◽  
Bending Loads ◽  
A Current ◽  
Water Depths ◽  
Over Time

In previous Spar designs where pull tubes were used to board the risers (either export or flowline risers), the pull-tube extended a considerable distance beyond the keel and used a tapered design to form a bend restrictor that supported the riser throughout the riser/hull interface. In a current Spar design, the pull-tube is terminated at the hull keel and the bending loads are carried by a double sided stress-joint in the riser that pivots on a centralizer located near the bottom of the pull-tube. Essentially, this is an adaptation of the double-sided stress joint used for top tensioned risers exiting the bottom of their buoyancy can stems to the similar condition of an SCR exiting a pull tube terminating at the Spar’s keel. This new pull-tube and SCR configuration can be applied for both Truss and Classic Spars. SCRs boarding Spars through pull tubes have several advantages over stress joints or flex-joints anchored in porches, notably, eliminating both the need for divers to make large piping connections at 500′ to 600′ water depths and the possibility of those connections leaking over time. Moving the bend restrictor function from the pull tube to the riser provides the additional advantage of adding flexibility for the Spar to accommodate future risers whose size and weight are not known at the time the pull tubes are designed and the platform is installed. With the stress joint as part of the riser, the bend restrictor can be custom designed for each riser since the pull tube works the same for all risers. The SCR and stress joint, pull-in and in-place analyses have been performed by using the finite element program ABAQUS. The nonlinear capabilities of ABAQUS including the hybrid, gap and contact element formulations are utilized in the analysis of the pull-in process. The nonlinear contact elements with finite sliding capability are modeled with an exponential over-closure relationship.

An Efficient Time Domain Code for Strength and Fatigue Analysis of Steel Catenary Risers

2015 ◽  
Author(s):  
Djoni E. Sidarta ◽  
Xiaoning Jing ◽  
Kostas F. Lambrakos ◽  
Roger W. Burke ◽  
William C. Webster
Keyword(s):  
Time Series ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Time Domain ◽  
Fatigue Analysis ◽  
Strength Analysis ◽  
Analysis Software ◽  
Finite Element Program ◽  
Element Program ◽  
Steel Catenary Risers

Steel Catenary Risers (SCRs) are commonly used in the offshore industry. Strength and fatigue performance of SCRs due to waves, currents and vessel motions is typically calculated using time domain dynamic analysis. Strength analysis may involve a large number of load cases for different environments, riser conditions and vessel configurations. Fatigue analysis may involve computation of riser response for hundreds of fatigue sea-states. It is very important for project schedule and cost that the analysis software used is both accurate and computer efficient. This paper presents RodDyn as an alternative time domain analysis tool for SCR strength and fatigue analysis. RodDyn is a finite element program for dynamic analysis of single-pipe risers. Several publications on this program are available in the literature. The results of dynamic analysis of an SCR for strength and fatigue from RodDyn are compared against the results from ABAQUS. ABAQUS is a general finite element program that has been widely used in the offshore exploration and production industry and has been considered one of the standard finite element programs. Riser dynamic analysis uses time series of vessel motions due to metocean environments at an oblique angle to the plane of the SCR. Von Mises stress per API RP 2RD, strength checks per API STD 2RD and fatigue damage along the riser are presented for both RodDyn and ABAQUS. Time series of effective tension and bending moments at selected locations on the riser are also compared. The main advantage of using RodDyn for riser analysis is the speed of computation. This paper shows that RodDyn can deliver significant gains in computational speed compared to standard riser analysis software programs without sacrificing accuracy of the computed results.

scholarly journals The impact of drilling and slitting construction on damage field: evolution characteristics in low-permeability coal seam

2021 ◽  
Vol 37 ◽  
pp. 205-215
Author(s):  
Heng Chen ◽  
Hongmei Cheng ◽  
Aibin Xu ◽  
Yi Xue ◽  
Weihong Peng
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Secondary Development ◽  
Distribution Area ◽  
Finite Element Program ◽  
Element Program ◽  
Mining Face ◽  
The Impact

ABSTRACT The fracture field of coal and rock mass is the main channel for gas migration and accumulation. Exploring the evolution law of fracture field of coal and rock mass under the condition of drilling and slitting construction has important theoretical significance for guiding efficient gas drainage. The generation and evolution process of coal and rock fissures is also the development and accumulation process of its damage. Therefore, based on damage mechanics and finite element theory, the mathematical model is established. The damage variable of coal mass is defined by effective strain, the elastoplastic damage constitutive equation is established and the secondary development of finite element program is completed by FORTRAN language. Using this program, the numerical simulation of drilling and slitting construction of the 15-14120 mining face of Pingdingshan No. 8 Mine is carried out, and the effects of different single borehole diameters, different kerf widths and different kerf heights on the distribution area of surrounding coal fracture field and the degree of damage are studied quantitatively. These provide a theoretical basis for the reasonable determination of the slitting and drilling arrangement parameters at the engineering site.

Finite Element Analysis on the Deformation of Energy-Saving Wire-Mesh Frame Wallboard

2014 ◽  
Vol 501-504 ◽  
pp. 731-735
Author(s):  
Li Zhang ◽  
Kang Li
Keyword(s):  
Finite Element ◽  
Energy Saving ◽  
Theoretical Basis ◽  
Steel Wire ◽  
Wire Mesh ◽  
Design Parameters ◽  
Element Analysis ◽  
Finite Element Program ◽  
Element Program ◽  
Influence Degree

This paper analyzes the influence degree of related design parameters of wire-mesh frame wallboard on deformation through finite element program, providing theoretical basis for the design and test of steel wire rack energy-saving wallboard.

scholarly journals Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Muhammad Auchar Zardari ◽  
Hans Mattsson ◽  
Sven Knutsson ◽  
Muhammad Shehzad Khalid ◽  
Maria V. S. Ask ◽  
...  
Keyword(s):  
Finite Element ◽  
Seismic Event ◽  
Deformation Behaviour ◽  
Ground Surface ◽  
Tailings Dam ◽  
Limited Extent ◽  
Northern Sweden ◽  
Finite Element Program ◽  
Dynamic Analyses ◽  
Element Program

Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes.

A preprocessor for the finite element program SAP IV

1981 ◽  
Vol 17 (12) ◽  
pp. 1779-1789
Author(s):  
E. Haugeneder ◽  
W. Prochazka ◽  
P. Tavolato
Keyword(s):  
Finite Element ◽  
Finite Element Program ◽  
Element Program

Abstract 2871: Saddle-Shaped Annuloplasty Reduces Mitral Leaflet Stress: A Real-Time 3D Echocardiographic Study

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Aaron S Blom ◽  
Chun Xu ◽  
Liam P Ryan ◽  
Benjamin Jackson ◽  
Landi M Parish ◽  
...  
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Stress Reduction ◽  
Heart Association ◽  
Posterior Leaflet ◽  
Volume Data ◽  
Medical Systems ◽  
Annuloplasty Ring ◽  
Finite Element Program ◽  
Element Program

Objectives: High leaflet and chordal stresses contribute to recurrent mitral regurgitation after repair procedures. We hypothesized that a saddle-shaped annuloplasty ring would reduce leaflet stress compared to a similarly sized flat annuloplasty ring. To test this hypothesis we used a novel 3D echocardiographically-based finite element modeling (FEM) technique for quantifying regional mitral valve stress. Methods: Real-time 3D echocardiography was performed in 8 sheep before and after placement of either a 30mm flat annuloplasty (n=4) or a 30mm saddle-shaped annuloplasty. Full-volume data sets of the MV were obtained using an IE33 platform(Philips Medical Systems, Andover, Massachusetts) and exported to Cardio-View (Tomtec Imaging Systems, Munich, Germany) for image analysis. Individual leaflet data were then interpolated using Matlab (The Mathworks, Natick, Massachusetts). Triangulated leaflet surfaces were extracted and the data imported into a commercial finite element program (ABAQUS/Explicit 6.3, HKS Inc. Pawtucket, RI) to quantify regional stress distributions in all segments (P1, P2, P3 and A1, A2, A3) of the MV. Results: Peak anterior and posterior leaflet stresses after flat annuloplasty placement were 0.20±0.001MPa and 21±0.02MPa. Peak anterior and posterior leaflet stress after saddle-shaped annuloplasty placement was 0.19±0.02MPa and 13±0.01MPa (p<0.05 for the posterior leaflet stresses) Conclusions: Saddle-shaped annuloplasty design results in greater stress reduction in the posterior leaflet than standard flat annuloplasty rings and may, therefore, result in more durable repairs. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

Study on Crashworthiness Characteristics of Several Concentric Thin Wall Tubes

2010 ◽  
Author(s):  
Parisa Hosseini Tehrani ◽  
Sajad Pirmohammad
Keyword(s):  
Finite Element ◽  
Optimum Combination ◽  
Thick Wall ◽  
Thin Wall ◽  
Finite Element Program ◽  
Linear Dynamic ◽  
Wall Structures ◽  
Moving Body ◽  
Oblique Loading ◽  
Element Program

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.

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